Abstract
PurposeIn this work, we investigated the effect on the workflow and setup accuracy of using surface guided radiation therapy (SGRT) for patient setup, megavoltage cone beam CT (MVCBCT) or kilovoltage cone beam CT (kVCBCT) for imaging and fixed IMRT or volumetric‐modulated arc therapy (VMAT) for treatment delivery with the Halcyon linac.MethodsWe performed a retrospective investigation of 272 treatment fractions, using three different workflows. The first and second workflows used MVCBCT and fixed IMRT for imaging and treatment delivery, and the second one also used SGRT for patient setup. The third workflow used SGRT for setup, kVCBCT for imaging and VMAT for delivery. Workflows were evaluated by comparing the number of fractions requiring repeated imaging acquisitions and the time required for setup, imaging and treatment delivery. Setup position accuracy was assessed by comparing the daily kV‐ or MV‐ CBCT with the planning CT and measuring the residual rotational errors for pitch, yaw and roll angles.ResultsWithout the use of SGRT, the imaging fields were delivered more than once on 11.1% of the fractions, while re‐imaging was necessary in 5.5% of the fractions using SGRT. The total treatment time, including setup, imaging, and delivery, for the three workflows was 531 ± 157 s, 503 ± 130 s and 457 ± 91 s, respectively. A statistically significant difference was observed when comparing the third workflow with the first two. The total residual rotational errors were 1.96 ± 1.29°, 1.28 ± 0.67° and 1.22 ± 0.76° and statistically significant differences were observed when comparing workflows with and without SGRT.ConclusionsThe use of SGRT allowed for a reduction of re‐imaging during patient setup and improved patient position accuracy by reducing residual rotational errors. A reduction in treatment time using kVCBCT with SGRT was observed. The most efficient workflow was the one including kVCBCT and SGRT for setup and VMAT for delivery.
Highlights
In recent years there has been a growing interest in the assessment of the performance and quality of the treatment delivery process for external beam radiotherapy,[1,2,3,4] favoring a more efficient and safer clinical practice
Without the use of surface guided radiation therapy (SGRT), additional imaging fields were necessary in 11.1% of the fractions
Once SGRT was incorporated into the workflow, the percentage of fractions requiring more than one imaging field was reduced to 5.5% (Table 2)
Summary
In recent years there has been a growing interest in the assessment of the performance and quality of the treatment delivery process for external beam radiotherapy,[1,2,3,4] favoring a more efficient and safer clinical practice. Time‐efficient workflows during radiotherapy treatments allow for a higher clinical throughput, improved patient comfort and reduced costs per treatments by reducing the machine and staff hours Achieving such efficient workflows require a thorough assessment and optimization of each stage of the treatment process, including patient setup, image‐guided evaluation and delivery of the treatment fields. Compared with the rotational speed of a C‐arm linac, Halcyon speeds are up to four and two times higher during the imaging and dose delivery stages, respectively. Such increased rotational gantry speeds, combined with a higher multileaf collimator (MLC) leaf speed allow for faster treatments. The plan quality with Halcyon was maintained but the imaging and dose delivery times were reduced as compared with treatments using a C‐arm linac
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